Morrisons said that as of the end of July, the cost of crude oil was 66% above a year earlier, wheat up 23% while rice prices had more than doubled.

Although the fierce competition between supermarkets meant it could not pass on all increases to customers, the group remains on track to hit profit targets this year despite the toughest trading environment for years.

"We fully expect the second half to be highly competitive as disposable incomes come under further pressure, and we will continue to use our sales momentum to fund price investment and maintain a strong competitive position," the group said.